1. Field of the Invention
The present invention is directed to a control device for a light emitting diode (LED) light engine, and more particularly to a control device that can efficiently control a drive current provided to the LED light engine.
2. Description of the Background Art
Light engines including LEDs as light sources are well known. An LED as a light source degrades over time, in contrast to an incandescent lamp that operates at a given light output and then at a specific time bums out and ceases to operate at all.
One manner to compensate for the long term degradation of light output by an LED is to initially drive the LED with a much higher driving current than is necessary for a desired light output. For example, an LED can be initially driven with a drive current at, for example, 30% higher than required for a desired light output. In that manner when the LED slowly degrades over time, the light output from the LED will decrease, but the light output can decrease 30% and still output the desired amount of light. For example in this instance if a LED degrades to output 30% less light over five years, then by initially driving the LED with 30% greater drive current than necessary to have a 30% greater light output, the LED will properly operate for five years before its light output falls below a desired level.
Further, in such a background system when the LED finally outputs less light than desired, i.e. in this example when the light output is degraded by greater than 30%, no clear indication is provided that the light output from the LED has significantly decreased or fallen below a determined threshold.